Tg is the glass transition temperature of the PCB material and very important parameter.

At this temperature the raw PCB material changes from stiff glass-like material to a elastic and bendable plastic-like material.

The biggest problems in the PCBs during the assembly is the Z-axes thermal expansion as above Tg temperature PCB expands rapidly and if kept long time about Tg temperature the small PCB vias may/will crack internally.

The most evil part is that when the PCB cool off the vias will shrink and may still give unreliable contact like touching together two copper wires, but later with temperature changes, vibration moisture these internal cracks in the vias can cause lost of electrical connections on random basis.

Tg 135 was commonly used and good enough for the old SnPb technology.

Since 2006 the new Lead Free technology require higher soldering temperatures and Tg 135 is not good choice.

PCBs assembled by ROHS lead free technology should be done with material with Tg 170 to be reliable. Especially this is valid for multilayer PCBs with small vias less 0.4 mm.

A64-OLinuXino first prototypes were made in March and lot of people wonder why we do not release for mass production this board yet 🙂 so we got lot of e-mails and I see there is need for blog post with update.

Here is the recap from the first prototypes:

RAM memory works at amazing 667Mhz clock much more than A20 and other boards and the board works stabile under stress tests for many hours

eMMC works fine, we didn’t test NAND Flash due to the missing Linux support probabbly this will stay just as option and we will assembly the boards with eMMC which is faster, better and in industrial temperature

Linux Kernel is 3.10.65 and works fine, we managed to run all peripherials

Audio In and Out is working

HDMI is working

USB host is working

USB-OTG is working

WiFi+BT is working

MIPI interface – no display which to use to test, any ideas?

HSIC interface – don’t know how to test, any ideas?

LiPo charger and step up works

LCD works

Ethernet Gigabit interface works just in master mode

While we worked on this board we found new PHY from Microchip which can be ordered in industrial temperature, we tested it with A20 and it works fine (we already have LIME2 version with it which is on prototype), so we decided to re-design the Ethernet part of A64-OLinuXino with it, this will allow us to produce A64-OLinuXino in industrial temperature grade -40+85C.

Another major upgrade for Rev.B is around eMMC interface, we re-designed it as per your feedback to be possible to work on programmable 3.3V and 1.8V thus to allow faster transfers.

Rev.B is routed at 90% we need 1 more week to complete it and run new prototypes. If everything goes smoothly we will be ready by end of the month.

Our next Help Day is this Saturday 26/09 at 11.00 o’clock in our training building.

If you need help with your project, or you don’t know how to use some of our boards you can come this Saturday at our Help day.

We got a number of requests to make KiCAD workshop in Plovdiv like the one we did in Sofia at Hack Conf this weekend, so if you want to get familiar with KiCAD you can come on the Help day with your laptop with KiCad pre-installed and to learn how to use it 🙂

We use KiCAD extensively this year and already got more than 20 boards designed with it, so we got some experience we can share.

We have been invited by Hack Conf 2015 organizers to make workshop and will take this opportunity to make small workshop about the Open Source PCB CAD program KiCAD.

The workshop will get you introduced to KiCAD, the flow of work, component library creation, schematic capture, PCB layout. At the end of the work shop you will be able to make your first small PCB with KiCAD and to prepare files for manufacturing.

Bring your computer with you and download and install KiCAD before you come. KiCAD can be download from http://kicad-pcb.org/